The present invention relates to an apparatus and method for automatically leveling a vehicle, such as a recreational vehicle, or a platform, such as an industrial platform, when the vehicle or platform is stationary and located on uneven terrain or an out-of-level surface. Specifically, the present invention relates to a microprocessor-based controller apparatus connected to four extendable legs mounted to the vehicle or platform, the controller interpreting an orientation signal corresponding to the vehicle or platform pitch and roll from a level sensor mounted on the vehicle or platform, to extend and retract the legs according to a predetermined method, thereby leveling the vehicle or platform.
Vehicles, such as recreational vehicles, are often parked at campsites or other locations on uneven terrain. Consequently, the comfort of the occupants of the vehicle while eating, sleeping, etc. within the vehicle, as well as the proper operation of some appliances such as refrigeration devices, may be adversely affected by the out-of-level orientation of the vehicle. Similarly, certain industrial devices require a level orientation for proper operation and are therefore mounted on platforms which may be leveled according to the teachings of the present invention. For simplicity, the remainder of this specification will describe the invention as used to level a vehicle although the apparatus and method described herein may have other applications.
It is known to employ jacks, blocks, or even hydraulically driven extendable legs mounted to a vehicle, to raise the low portions of the vehicle in an attempt to level a vehicle. Obviously, manual methods, such as using jacks and blocks, for leveling a vehicle the size of a recreational vehicle are undesirable. Manually leveling a vehicle may require raising one corner of the vehicle at a time, thereby inducing cross-frame stresses which may damage the vehicle frame. Additionally, manual jacks are potentially dangerous, time-consuming to use, inaccurate, and inconvenient, especially in bad weather or in cold or muddy conditions.
Manual actuation of hydraulically-driven extendable legs mounted to the vehicle frame is an improvement on the use of jacks to level a vehicle. However, even a skilled user attempting to level a vehicle by individually actuating extendable legs mounted to the vehicle may over extend a leg such that cross-frame stresses are imposed upon the vehicle. Additionally, the process of extending individual legs, manually checking the orientation of the vehicle using a level sensor, then further adjusting the orientation of the vehicle by extending another leg, is time consuming and inaccurate.
The present invention provides a microprocessor controlled system for actuating adjustable legs mounted to the vehicle frame according to a predetermined method of actuation and in response to vehicle orientation feedback signals provided by a level sensor mounted to the vehicle. The leveling process is initiated by the user by actuating a switch and then proceeds automatically through the leveling process until level is achieved, a system error occurs, user abort is detected, or a time-out period is exhausted, such as three minutes.
The system generally includes four adjustable legs mounted adjacent the respective corners of the vehicle, each leg being independently extendable and retractable between an extended position and a stowed position, a level sensor mounted to the vehicle for sensing the pitch and roll of the vehicle relative to a reference level plane, the level sensor providing an orientation signal representing the vehicle pitch and roll, a sensor controller coupled to the level sensor which selects, measures, converts, and reports the orientation signals, and a main controller including a memory for storing data representing the reference level plane, and responding to user commands to extend or retract the legs, or level the vehicle by carrying out the automatic leveling process.
The method for leveling the vehicle includes sequentially actuating the legs so that they move from their stowed position to their extended position. The level sensor provides an orientation signal to the main controller which changes when each leg engages the ground and moves its respective corner of the vehicle slightly upwardly. The main controller interprets this orientation signal and stops actuating that leg. This process continues until all legs firmly engage the ground. Next, the main controller reads the present orientation signal from the sensor and compares it to the reference level plane stored in the system memory to determine which end and side of the vehicle are below the reference level plane. The controller individually actuates the legs at the low end of the vehicle by individually extending each of the legs for a predetermined period of time. The main controller then individually actuates the legs at the low side of the vehicle, individually extending each in a similar fashion. The main controller continues alternating between upward adjustments of the low end and the low side until one of the end or the side are moved to a position above the reference level plane as indicated by the level sensor. During the next iteration, the high end or side is lowered instead of raised by individually retracting the legs at the high end or side for a predetermined period of time which is less than the time period used to raise the legs. This process continues as the main controller alternates between adjusting the end and the side, reversing the direction and reducing the time period of actuation of the legs each time an end or side passes through the reference level plane until level is reached.